湖南典型土壤磷素剖面分布特征及其流失风险

The Study of Distribution Characteristics of Phosphorus of Typical Soils in Hunan and Its Loss Risk

为了明晰不同土壤类型、利用方式土壤磷素分布特征,评估其流失风险的大小,研究了湖南3种典型土壤(红壤、潮土、紫色土)磷素含量特征及其剖面分布。野外采集3种母质发育土壤的旱地和水田土壤剖面样品进行室内分析,按张守敬等提出的酸性土壤无机磷形态的分级测定方法,对土壤无机磷进行分级。结果表明,不同土壤中磷素含量和形态分布有明显差异:磷素含量由高到低依次为潮土>红壤>紫色土;红壤发育的土壤以磷酸铝和磷酸铁占优势,潮土和紫色土的Ca-P含量占优势较高。土壤磷素在剖面中的分布均为表层最高,且随剖面深度的增加而减少,而后趋于相对稳定;无机磷中的Al-P、Fe-P以及O-P主要集中在0～20cm的土层中,其剖面分布于全磷类似,而Ca-P剖面分布上相对变化不大。土地利用方式的不同导致全磷的差异:水田均大于旱地。土壤类型及利用方式均对磷素含量和形态特征有明显影响,应根据不同的土壤类型和利用方式控制其流失风险。

In order to clarify the distribution characteristics of phosphorus in different types and use patterns of soil and assess the risk of phosphorus ＇ s loss,the content and profile distribution of phosphorus in three typical soils（red soil,alluvial soil,purple soil） was studied.Samples of dry land and paddy soil profile,coming from three parent materials,collected in the field were analyzed in laboratory to classify the inorganic phosphorus according to the fractional analysis method in acidic soil proposed by Zhang Shoujing.The results showed that：the levels and forms in different soil showed a marked difference：the sequence of phosphorus content from high to low was alluvial soil,red soil,purple soil.Al-P and Fe-P had a high percentage in acidic soil,while Ca-P in alluvial soil and purple soil.Phosphorus ＇ s level was the highest in surface soil,and then its content decreased firstly and then tended to be relatively stable.Al-P,Fe-P and O-P mainly enriched in 0-20 cm soil layer and their distribution trend in the profile was similar to the total P,yet Ca-P had a little change in the profile.Because of different land use pattern,the content of the total P also showed a difference：paddydry land.Different types and utilization of soils had a significant effect on content and morphological characteristics of phosphorus,so the control of the risk of phosphorus ＇ loss should be based on different soil types and utilization.